Dr. Zhang’s group is expected to receive two EPA P3 awards again, which is the second time that two EPA awards have been received at the same time. The two project scopes/descriptions are as follows and are expected to start early March, 2025 for two years.
https://cfpub.epa.gov/ncer_abstracts/INDEX.cfm/fuseaction/display.abstractDetail/abstract_id/11563
Description:
Nanobubbles in water exhibit unique physicochemical and fluid dynamic properties than ordinary macrobubbles. For example, nanobubbles have a long residence time in water due to their low buoyancy and high stability against coalesces, collapse or burst, and the formation of bulk bubbles. Nanobubbles have a higher efficiency of mass transfer compared to bulk scale bubbles due to the high specific surface areas. The high specific surface also facilitates physical adsorption and chemical reactions in the gas liquid interface. The collapse of nanobubbles creates shock waves, which in tum, promotes the formation of hydroxyl radicals (•OH), which may promote degradation of organic matters or disinfection. With respect to foam fractionation, the high surface areas and hydrophobicity of nanobubbles could effectively adsorb and immobilize hydrophobic organic contaminants such as PFAS. This project embarks on nanobubbles to establish foams in water and remove PFAS via a green fractionation separation process that appear to have low energy footprints and leave no chemical residuals. Besides research efforts, new course modules and hands-on experiments will be developed to integrate the research activities into student engagement and education. Undergraduates and graduates in different STEM disciplines (e.g., civil, chemical and environmental engineering) will be recruited to participate in the research project tasks under PI’s team’s mentorship.
Objective:
Perfluoroalkyl and polyfluoroalkyl substances (PFAS), with their omnipresent presence in the environment and toxicity, have recently drawn substantial attention. Without proper treatment, PFAS in wastewater may pollute the subterranean ecosystems, causing pollution to surface water and groundwater. To mitigate PFAS pollution and health impact, different water treatment processes or technologies have been demonstrated including adsorption by powdered activated carbon (PAC) or granulated activated carbon (GAC), anionic ion exchange, nanofiltration (NF), and reverse osmosis (RO). However, they either suffer from high operational cost or insufficient removal ability for PFAS in wastewater with complex water matrixes. This project aims to develop a nanobubble-enabled foam fractionation process to remove PFAS from wastewater. The project will examine (1) the colloidal properties of nanobubble foam under variations of water chemical properties such as pH changes, salinity and presence of co-existing natural organic matters and synthetic surfactants, (2) the removal efficiency of PFASs with different carbon chain lengths in synthetic water and real water that may simulate contaminated ground water, landfill leachate and brine wastewater from regenerate backwash processes in reverse osmosis membrane filtration and ion exchange, (3) comparison of PFAS removal performances of foam fractionation using nanobubbles, microbubbles and macro bubbles that may yield different foaming ability and structures. The project findings will provide an insight for novel low-cost and sustainable water purifying technologies for complex wastewater. The scientific merits from this project include: (1) increasing the removal efficiency of the recently most concerned contaminant PFAS under exposure to nanobubble ebullition, and thus to evaluate the possibility of practical application on the field for the economic feasibility; (2) unraveling the intriguing interaction mechanisms between nanobubbles, water, and contaminants.
Expected Results:
The anticipated research outputs include peer-reviewed journal articles, conference presentations, novel PFAS removal technique, patent applications and project reports. Moreover, research seminars will be run collaboratively with industrial partners and collaborators such as landfill leachate treatment facilities in New Jersey. The potential project outcome includes transformative knowledge to alleviate water contamination in different affected small, rural, tribal and/or underserved communities or areas. The effective means to mitigate PFAS and other emerging co-existing contamination such as heavy metals, solvents or chemical additives and pharmaceutical residuals from impaired water bodies can improve human health and well-being and also boost environmental quality, aesthetic values, economic competitiveness. The measure of success is the numbers of peer-reviewed journal publications or presentations, feedback from our industrial partners or collaborations and community engagement via seminars and presentations during or after the project period.
Supplemental Keywords:
nanobubbles, PFAS, foam fractionation, restoration
Description:
This project embarks on a green soil rinsing or cleaning process using fine bubbles-enriched water to enhance the oil desorption, mobilization and removal from contaminated soil matrix. Nanobubbles in water have repeatedly been reported to exhibit unique physicochemical and fluid dynamic properties that macrobubbles or microbubbles do not have. For example, nanobubbles have a long residence time in water due to their low buoyancy and high stability against coalesces, collapse or burst, and the formation of bulk bubbles. Nanobubbles have a higher efficiency of mass transfer compared to bulk scale bubbles due to the high specific surface areas. The high specific surface also facilitates physical adsorption and chemical reactions in the gas liquid interface. The collapse of nanobubbles creates shock waves, which in turn, promotes the formation of hydroxyl radicals (•OH), which may even promote degradation of organic matters or disinfection under proper conditions (e.g., sonication agitation or UV irradiation). With respect to soil remediation, the high surface areas and hydrophobicity of nanobubbles could effectively adsorb, immobilize and detach soil contaminants such as heavy metals and hydrophobic organic pollutants. Non-toxic gases such as oxygen (O2), carbon dioxide (CO2) or hydrogen (H2) could be used to produce nanobubbles in water for rinsing the contaminated soil. We hypothesize that due to their different redox potentials and chemical impacts, different gaseous nanobubbles may result in different oil-bubble and soil-bubble interactions, which ultimately affect oil removal from contaminated soil. Our prior study discovered that CO2 nanobubbles achieved the highest leaching rate of Pb from soil, followed by CH4 and H2 nanobubbles. Moreover, the CO2 nanobubble water rinse resulted in different leaching kinetics of different metals (Pb, Cu, Zn, and Cr) from the contaminated soil column. Thus, this project will reveal new insights into the oil removal and leaching mechanisms under different conditions and potentially result in a transformative solution to address soil remediation. The research findings will potentially enable a greener soil rinsing process that could reduce or even eliminate the use of synthetic chemicals such as surfactants or solvents that could harm our environment or human health. Besides research efforts, new course modules and research seminars will be developed to integrate the research activities into student engagement and education to showcase our sustainable soil treatment approaches. Undergraduates and graduates in different STEM disciplines (e.g., civil, chemical and environmental engineering) will be invited to participate in these research seminars or the research project tasks under PI’s team’s mentorship.
Objective:
Extensive industrial and agricultural activities as well as wastewater discharge or surface runoff bring tons of pollutants such as heavy metals, organic solvents, chemical fertilizers and pesticides and cause soil pollution. New Jersey, for instance, has many brown sites and superfund sites in the US that are characterized by persistent legacy soil or water contaminants that must be treated to prevent human exposure. Soil remediation is critical to prevent surface water or groundwater pollution, protect human health and improve agricultural product quality. Conventional soil remediation includes soil washing/flushing, thermal desorption, vitrification, photocatalyst and bioremediation, which, however, are relatively expensive, time consuming and chemically intensive. This project aims to develop a green and powerful washing process using nanobubbles water for soil contaminant removal. The project will examine (1) the removal of oil (e.g., diesel and gasoline) from simulated contaminated soil through nanobubble water mixing and washing under various conditions (e.g., sonication and surfactant addition); (2) the mechanisms of interaction between different types of nanobubbles (e.g., CO2 and O3), soil and contaminants. The project findings will provide an insight for novel chemical-free and sustainable soil cleaning technologies for remediation of contaminated soil.
Expected Results:
The anticipated research outputs include peer-reviewed journal articles, conference presentations, soil washing protocols, patent applications and project reports. Moreover, educational activities will be run collaboratively with industrial partners in soil remediation companies. The potential project outcome includes transformative knowledge to alleviate soil contamination in different affected small, rural, tribal and/or underserved communities via devising this novel soil washing technique or process using nanobubbles. Consequently, the soil decontamination can improve human health and well-being and also boost environmental quality, aesthetic values, economic competitiveness. The measure of success is the numbers of peer-reviewed journal publications or presentations, workshop attendance/feedback, industrial collaborations for future pilot studies or commercialization.
Supplemental Keywords:
nanobubbles, oil, soil remediation, soil washing
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